The challenge was submitted on the last legally possible day in Jones County, the county circuit-court clerk’s office confirmed.
Mr. McDaniel and his attorney, Mitchell H. Tyner, ask for an injunction to suspend the certification of Mr. Cochran as the Republican nominee for the fall general election and to delay his name from being officially placed on the ballot.
Mr. McDaniel and his campaign team have charged that there were thousands of voting irregularities in the runoff, which Mr. Cochran won by 7,667 votes after courting voters in heavily Democratic regions of the state.
“In combination with Senator Cochran’s intentional solicitation of Democrat voters to violate state law, the permitted unlawful votes produce an outcome that does not express the will of qualified Republican party electors,” the petition says.
Under state law, voters are free to “cross over” and vote in the opposite party’s primary, but they cannot vote in both. If someone voted in the Democratic contest June 3 and then crossed over to vote in the June 24 GOP runoff, for example, that vote would be rendered invalid.
In somewhat of an oddity, the names of Mr. Tyner himself and his wife, Sloan, were included on a list of hundreds of such questionable voters circulated earlier in the week.
Mr. McDaniel also asked that results from Hinds County and other counties “proved to have permitted widespread vote fraud and violations of Mississippi election law” be thrown out.
Alternately, Mr. McDaniel asks the court to order a new primary runoff.
State law dictates that a state Supreme Court justice will now appoint a senior justice outside of Jones County to handle the case, according to The Clarion-Ledger newspaper of Jackson.
Any decision would likely have to happen quickly for another runoff to be held; state law dictates that sample ballots are supposed to get to local officials by Sept. 10.
Mr. McDaniel’s team and tea party groups have blasted Mr. Cochran’s campaign for relying on Democrats and black voters to put Mr. Cochran over the top in the open race. Mr. Cochran’s camp has said he won the race fairly and that any voting discrepancies are small enough that they could be chalked up to human error.
Butler Snow law firm, representing Mr. Cochran’s campaign, said in a statement they’d be prepared.